1. Field of the Invention
The invention relates to the field of apparatus for packing fruit into shipping cartons, and in particular to a mechanism for operating plates used for guiding the fruit into the carton within a carton packing machine.
2. Description of the Prior Art
Storage, handling, shipping costs and presentation of fruit quality are optimized if fruit is graded by size so that fruit having approximately the same size is compactly stored in ordered arrays within the cardboard shipping cartons. The number of fruit as well as the security of the fruit within the shipping carton is increased by packing in a dense array. For example, it is well known to pack fruit, such as citrus fruit, into rectangular cartons in what may be considered a body-centered cubic lattice array. The cubic nature of the array allows the fruit to completely fill the rectangular cardboard carton. The body-centered arrangement allows the density of fruit to be increased as well as the security of positioning of the fruit within the carton so that the fruit position is unlikely to shift as the box is moved. A body-centered array is defined as being constructed of unit cubes having an item of fruit at each of the eight corners of the cube with a ninth item of fruit positioned at the center of the cube. Each item of fruit touches the adjacent fruit. Alternatively, the structure may be visualized as having a layer of fruit laid down in a rectangular array with a second layer of fruit laid thereover which is offset from the underlying layer, so that each fruit in the overlying layer rests in the interstitial depression defined by four of the fruit in the underlying layer. The next or third layer which is placed over these two layers again is offset so that each item of fruit lies in an interstitial space in the underlying layer. The layers continue to be offset as they are stacked within the carton up to the upper most level of the carton. The carton is thus fully packed with what may be referred to as alternating "A" and "B" layers. Examples of such devices are shown in U.S. Pat. No. 5,117,611.
FIG. 1 shows a citrus fruit packing machine, which incorporates some of the features of the prior art, although the specific machine in FIG. 1 depicts the improvement of the invention. The fruit packer, generally denoted by reference number 10, receives fruit from a sorting conveyor apparatus, not shown, which feeds the fruit to an "A" tray 12 and "B" tray 14. The fruit is supplied from behind packer 10 and is rolled down channels 16 until it meets a stop 18 so that a properly oriented array of fruit is assembled on trays 12 and 14.
An "A" fruit handler 20 and "B" fruit handler 22 then alternately move from the location of its corresponding "A" tray 12 or "B" tray 14 respectively on the left and right positions within packer 10 as depicted in FIG. 1 to a center packing position 24.
A rectangular cardboard carton 26 is carried up by a conveyor underneath packer 10 to center packing position 24. The cardboard carton 26 is a deep rectangular box having a closed bottom, four connected adjacent sides, and flaps leaving the top of box 26 open. The flaps are later folded and sealed. Relevant portions of the open carton are better depicted in FIGS. 5-7. Carton 26 as shown in FIGS. 5-7 remains beneath a table 28 of packer 10.
Each fruit handler 20 and 22 has a plurality of suction fingers 30 provided on their lower surface. Fingers 30 on "A" handler 20 will temporarily affix themselves to the underlying fruit when the "A" handler 20 is lowered onto "A" tray 12 by virtue of vacuum supplied through a manifold to each of fingers 30. Fingers 30 are flexible so that they center themselves on the underlying fruit. One item of fruit is temporarily picked up by each finger 30 by means Of the vacuum supplied to the center of finger 30 which is formed to have a suction cup seal on its end. As fruit handler 20 is lifted, an entire "A" layer is lifted from "A" tray 12. Handler 20 is then moved to center position 24 at which point it descends to positively position or place the fruit within cardboard carton 26. At this time the suction is released, handler 20 pulled upwardly and out of carton 26, leaving the oriented fruit forming a complete packed "A" type layer in position within carton 26.
Similarly, "B" handler 22 picks up a complete layer of fruit from "B" tray 14 in a "B" arrangement through flexible fingers 30 and moves to a loading position 24, as the now empty handler 20 moves to the right in FIG. 1 to pick up a new "A" type layer. Meanwhile, "B" handler 22 moves downwardly into the loading position to place a "B" type layer of fruit on the top of the underlying "A" layer in carton 26. The "B" layer of fruit will be placed in the interstitial regions between the fruit in the "A" layer. Suction is then released on "B" handler 22 which is then moved upwardly and out of cardboard carton 26. "B" handler 22 then moves to the left of FIG. 1 to pick up a new layer as "A" handler 20 moves to the left of FIG. 1 bringing in a new "A" layer. In this way, "A" and "B" layers are alternately placed in carton 26 until filled. Upon being filled after a predetermined number of layers, the carton is moved by the underlying conveyor from packer 10 to be sealed and processed, as an additional carton 26 is then brought into position for filling.
However, as a practical matter, it must be understood that the flexible fingers 30, for various reasons including the fastening on fruit of differing diameters at different points over center, will pick up a layer of fruit which will be splayed outwardly from the edges of handler 20 or 22. The fruit will not be compactly compressed into a minimum rectangular envelope when first picked up. Each fruit will not be in physical contact with each of the adjacent fruit but may, depending upon any number of reasons, be slightly spaced apart from the adjacent fruit. In this splayed condition, it is therefore impossible to place the fruit within the smaller rectangular cross sectional envelope of cardboard carton 26 unless the fruit is first compressed into the desired maximum rectangular envelope.
In the prior art, the compression of the fruit to the maximum rectangular envelope was accomplished by means of four guide plates positioned around the packing opening 32 and packer table 28. These guide plates were pneumatically actuated through electromechanical controls so that the splayed fruit was placed downward within central packing position 24 with the guide plates similarly splayed open to accept the fruit. When handler 20 or 22 was at the right depth, the guide plates were then moved into place by means of pneumatic actuators to compress the fruit within the rectangular outline of the packing carton so that handlers 20 or 22 could be permitted. to continue downwardly to position the fruit within the carton in a dense array. Handlers 20 and 22 then moved upwardly and out of the carton and the guide plates were then driven open by means of the same pneumatic actuators in preparation for accepting the next placement of fruit.
While such pneumatically actuated guide plates worked well, their controls were complex and were subject to breakdown. It is necessary for packer 10 to operate over long periods of time without breakdown, filling hundreds of thousands of cartons quickly and reliably. The pneumatically actuated guide plates were by far the most unreliable part of packer 10 and required constant adjustment and repair.
Therefore, what is needed is some type of actuating mechanism which can be used as part of a guiding mechanism in a packer 10 as used in the prior art, but which is not subject to the problems of complexity, reliability and adjustment which typifies prior art guide plates.